Field of the Invention
Embodiments of the present invention relate to field of display, and particularly, to a method and a device of estimating an image sticking grade of a display.
Description of the Related Art
In field of flat panel display, a liquid crystal display (LCD) becomes applied increasingly in high-performance display field due to compact volume, low power consumption, non-radiation and low manufacturing cost.
In order to improve performance and quality of a LCD, it is necessary to measure and estimate performance indexes of the LCD in the process of manufacture, such as, resolution, brightness, contrast degree, color gamut, response time, Mura, and image sticking grade, etc. The image sticking exists in a common LCD. Specifically, when the LCD is driven to display a certain still frame for a long time, ions in the LCD panel may be moved toward upper and lower substrates of the LCD along an electrical field direction and accumulated on a liquid crystal alignment layer. The accumulated ions may create an inner electrical field. When a next frame is displayed on the display, the accumulated ions on the liquid crystal alignment layer do not leave the liquid crystal alignment layer, which causes a residual direct-current voltage existing on the liquid crystal molecules. The residual direct-current voltage leads to the liquid crystal molecules being polarized and held at a certain rotated angle and thus being difficult to be changed. As such, the LCD will display images with defects. For example, the images in the previous frame will be remained on the display panel when the display is switched to display a next frame, which is a so-called image sticking. The image sticking may seriously impact image quality of the display.
In prior art, image sticking of a display is measured by human eyes or a test apparatus. However, as the process of observing the image sticking on the display by eyes is rather subjective and lacks accuracy, it is becoming obsolete in the process of production. The current test apparatus used to perform an image sticking test for a display is commonly configured to obtain the image sticking related data when the image sticking appears on the display and apply the data as basis to estimate an image sticking grade and the performance of the display.
However, the performance of the display in use is often affected by many factors, such as, displaying time, etc. The above image sticking grade can only be used to estimate the performance of the display at the moment that the image sticking appears and cannot fully and actually reflect the influence of the image sticking on the performance of the display in entire displaying process. Thus, by the current method of estimating the image sticking grade with inaccurate defects, it is impossible to fully and accurately estimate the image sticking of the display, thus the technicians cannot purposefully and completely modify the display on the basis of the defects caused by the image sticking, which leads a reduced product quality and a low ratio of good products.